Method of and apparatus for producing vapor saturation



June 2, 1936- J. c. HARRIS, JR 2,042,991

METHOD OF AND APPARATUS FOR PRODUC ING VAPOR SATURATION Filed Nov. 26,1934 Jeri/ 1,

Patented June 2, 1936 UNITED STATES METHOD OF AND APPARATUS FOR PRO-DUCING VAPOR SATURATION I James C. Harris, In, Baltlmore Md. ApplicationNovember 26, 1934, Serial No. 754,920 3 claim. (or. 230-208) Thisinvention relates to a method of and ap paratus for producingsubstantially constant saturation of a vapor under varying compresslonpressures and, among other objects, aims to provide improved means forinjecting a liquid into a compressor during the compression stroke andcontrolling the injection automatically in response to both thetemperature and the pressure of the vapor discharged from thecompressor. The idea is to reduce the energy required to pump a givenvolume of vapor or gas from one temperature and pressure to a highertemperature and pressure by injecting liquid into the cylinder duringthe compression stroke so that the final state of the delivered vapororgas is at a lower temperature than it would have been without liquidinjection and nearithe saturated condition. In short, the vapor iscompressed at constant quality and more vapor or gas is delivered fromthe cylinder discharge at the same pressure, but at lower temperature,with less expenditure of energy, on the same weight of vapor passingthrough the cycle. A unit weight of vapor has a definite latent heatcapacity at a given pressure; therefore, the

' greater weight delivered per unit of expanded energy, the greater theheat pumping capacity of the compressor. i

Other aims and advantages of the invention will appear in thespecification, when considered in connection with the accompanyingdrawing, wherein: r v

The figure is a diagrammatic illustratlonof one form of apparatuscapable of practicing the method.

In many industrial processes, such as the manufacture of artificial iceusing an ammonia compressor, for example, vapor is compressed toincrease both its temperature and pressure. When the vapor is compressedto a very high pressure, it is superheated. This invention, therefore,aims to provide a novel method of and apparatusfor producingsubstantially constant saturation of the vapor while it is undergoingcompression in order to reduce the power required to drive thecompressor for a given operation. To this end, the method involves theinjection of a liquid of' which the vapor undergoing compression iscomposed at a temperature preferably, though not necessarily, higherthan the temperature of the vapor in the cylinder at its finalcompression pressure and controlling tne injection of said liquid inresponse to relative variations in the pressure andtemperature of thevapor as it isdischarged from the compressor. The liquid is preferablyinjected into the cylinder in the form of a fog or very fine mist and isintroduced continuously during the compressionstroke so that it almostimmediately evaporates and commingles with the vapor undergoingcompression. For the purposes of this explanation, it will be assumedthat the compression 5 is adiabatic.

Referring particularly to the illustrative apparatus for practicing themethod, there is shown a vapor compressor l I) having a reciprocatingpiston II. The vapor is delivered from an evaporator to the cylinderthrough an intake conduit l2 and is discharged through an outlet conduitl3 leading to the heat exchanger. A spray nozzle ll, conveniently of thefuel injector type used in Diesel engines, is connected to dischargeintothe cylinder and is supplied with the saturating liquid through aconduit l5 by a variable discharge pump l6, also of the type generallyemployed in Diesel engines. The variable discharge pump is controlled inresponse to dlflerentials between pressure and'tem- 2o perature of thedischarged vapor. In this instance, a pressurestat, including a cylinderI1, is connected to the discharge outlet l3 by a conduit l8. A piston ISin the cylinder is acted upon by the vapor and is normally held in theposition shown by a coil spring 20 of the required compression strength.If desired, the strength of the spring may be varied in a well knownmanner to .vary the amount of delivered superheat. A piston rod 2|having rack teeth 22 meshing with a pinion 23 rotates or oscillates acam 24, the surface of which is shaped to correspond with thepressure-temperature curve setting of the particular vapor atsaturation. The cam will be different shapes for different vapors.

' In this example, the cam 24 acts on one end of a pivoted lever 25which is pivotally connected at its other end to a link 26. The pivot isshown as being mounted on a compression spring 21. A temperatureresponsive device is also connected v to the link 26. It is shown as.being of the fluid pressure type having a diaphragm on a diaphragmcasing 28 connected by a conduit 29 to a jacket 30 around the outletpipe IS. The arrangement is such that movement is imparted to the link'26 in response to diiferentials in pressure and temperature. This linkis connected to a control arm or member 3| of the variable dischargepump l6. As long as the pressure and temperature of the discharge vaporremain substantially constant, 59

the control mechanism will operate to deliver a constant quantity ofliquid to'the cylinder through the discharge nozzle I. If the vaporshould become superheated the quantity of liquid introduced will beincreased. The pressurestat and 2. thermostat are so connected thatthey-respond almost immediately to changes in pressure and temperatureof the discharging vapor. They are preferably arranged as near as isconvenient to the discharge outlet of the compressor.

Assuming that the temperature remains substantially constant while thepressure varies, cam 24 moves the lever 25 up or down which in turn,lower or raise the link 26. when the is lowered, more liquid isdischarged by the pump. When the pressure is constant and thetemperature varies, the diaphragm moves lever 25 cordingly. Of course,the effect of the temperature changes is modified by thepressure. As thearm 3| is moved down, the quantity of the saturating liquid injected isincreased. It will he understood that the pump is operatedintermittently in the same manner as the fuel pump for 21. Dieselengine. The driving mechanism forms no part of the present invention.

In some instances, it is desirable to employ means to indicate thecondition of the discharged vapor. For example, the liquid imector orthe pump may fail to function and the vapor will be superheated, causingthe normal troublsdue to excessive temperatures. In that case, anattendant should be notified of such condition. To that end, a suitableindicator, conveniently in the form of a pointer 32 on arm 3| cooperateswith a scale 33 to indicate the quality of the vapor by the positionofthe pointer. Also,'a suitable remote signal, in the form of a lamporbell 3| may be connected to the indicator to notify the attendant ofan abnormal condition.

It will be apparent to those skilled in the art that the illustrativecontrol mechanism is subject to wide variations and may takemanydiflerent forms. However, in all cases, the action of the temperatureresponsive menu will be modified by the pressure responsive means tooperate the control means. It is also contemplated that such controldevices will have a very wide application to industrial processeswherein compressed vapors are employed and that, by maintaining thecompressed vapors at substantially constant saturation an appreciableamount of power required for compression may be saved. For example, one

pound of ammonia vapor compremed adiabatiqally from a pressure of 34.28pounds absolute and F. toa pressure of 170 pounds absolute will requireapproximately 5% more energy than when compressed from" the samecondition to the same pressure and at a final temperature of 86 F. byinjecting approximately .105 poimd of atomthe range of temperatures andpressures for a iaed liquid ammonia into the cylinder, lowering thesuperheat and taking up this energy by changing the liquid ammonia intovapor or by taking up the heat of superheat by the latent heat of theliquid ammonia.

While the particular apparatus shown necessarily practices the describedmethod, it will he understood that the invention is not limited to suchapparatus. Moreover, it is not indispensable that all the features ofthe illustrative embodi ment thereof he used conjointly, since they maybe employed advantageously in various combine.- tions andsub-combinations.

What is claimed, is:

1. That method of producing substantially constant saturationof a vaporin a compression chamber under varying compression pressures whichcomprises injecting saturating liquid at a temperature above thetemperature due to final compression pressure into the vapor while it isundergoing compression and controlling the injection. automatically inresponse to both the temperature and pressure of the vapor immediatelyafter it leaves the compressor, throughout saturated condition of thedischarging vapor.

2. In combination with a vapor compressor of the character described, aspray nozzle connected to inject a saturating liquid in the form of afine mist into the compressor; a variable delivery pump connected to thenozzle; a thermostat responsive to the temperature of the vapor as it isdischarged from the compressor and connected to exercise a controllingeffect on the variable delivery pump; means responsive to the pressureof 35 the discharging vapor; and means connecting the pressureresponsive means to modify the controlling action of the thermostat inaccordance with the pressure temperature curve at saturation of theparticular vapor acted upon.

3. In combination with a vapor compressor of the character described,means connected to inject saturating liquid in the form of a fine mistinto the compressor; a variable delivery pump connected to supply saidsaturating liquid; temperature and pressure responsive devices connectedto the discharge side of the compressor and both arranged to control thevariable delivery pump in response to relative changes in pressure andtemperature; and a signal device connected to signify an abnormalcondition of the vapor.

JAMES c. mums, JR.

